- 3497 - UNIVERSE - Age of the Universe? The age of the Universe is 13,700,000,000 years and waiting for the next new discovery. The time is incomprehensible to our lives. And, the fact that we can comprehend the age of the Universe is truly amazing. Here is how we figured this out:
--------------------- 3497 - UNIVERSE - Age of the Universe?
- Gary needed a better explanation for how we learned the age of the Universe. It is a “step ladder approach“. Each step on the ladder takes us back in time until we get to the Big Bang.
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- We start with the age of the Earth. We learn that by determining the age of dirt. I know we say that Duane is older than dirt. But how old is dirt. We measure the radioactivity of dirt to learn how old it is.
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- Then the next step on the distance ladder is to learn the age of the Sun. Then the age of the Milky Way Galaxy. Then what is the oldest galaxy in the Universe and the Universe must be older than that. That gets us back to 13,700,000,000 years.
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- 13,700,000,000 years is time that is incomprehensible to our lives. And, the fact that we can comprehend the age of the Universe is truly amazing. Let’s get back to the age of Duane’s dirt that is radioactive.
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- The discovery of radioactivity reveled the existence of previously unknown sources of energy and unknown laws of physics. During radioactive decay electrons and protons are ejected along with gamma ray radiation.
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- It is the nuclear “Weak force’ that was holding those protons and electrons together in the form of neutrons inside the nucleus of atoms. It is the “Strong force’ that holds two protons together in the helium nucleus. These ejected helium nuclei particles from the nuclei were first known as “alpha rays“, or, radiation.
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- Radioactive decay is a natural process and it is responsible for much of the molten heat at the center of our planet. Uranium 238 is 99% or all naturally occurring uranium on Earth. It has a half life of 4,510,000,000 years. This happens to be the approximate age of the Earth.
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- If we take a sample of Uranium dirt and half of the radioactivity as decayed into a lighter stable element that is not radioactive then that is the “half life” of that radioactive material
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- Therefore, in Earth’s beginning there was twice as much U-238 as there is today. Uranium 235, a different isotope of uranium containing 3 fewer neutrons, makes up 0.7% of all naturally occurring uranium. It has a half life of 713,000,000 years.
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- By measuring the relative abundance of different radioactive isotopes scientists can date the origin of the many samples. Using this technique scientists have estimated the oldest natural rocks found on Earth to by 3,800,000,000 years old.
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- We said “natural rocks” because we meant not to include meteorites that have come to us from outer space. These rocks have been dated at 4,500,000,000 years. And, we think they are the same age as the Earth since the Earth is just a bunch of gravity smashed meteorites that got crunched together 4,500,000,000 years ago.
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- The energy of uranium was originally put there by an exploding supernova that produced such an enormous shockwave as to compress the outer layers of the star into higher lever, or heavier, elements. The star itself uses fusion and can only produce elements up to iron in atomic weight. It takes an explosion to produce those heavier elements.
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- A star starts by burning hydrogen. That process is the fusion of two hydrogen nuclei into one helium nuclei. Then the helium atom are fused into heavier elements like carbon, up to calcium, up to iron. Then fusion stops. Elements heavier than iron are radioactive and they slowly decay back to the element iron. That is what the uranium atoms are doing.
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- All elements lighter than iron release energy when fusion occurs. Iron is the first element to absorb energy when fusion occurs. When a star starts the fusion of iron its whole process of existence is reversed. Instead of releasing energy to counteract the pressure of gravity it absorbs energy and for the conservation of energy to be maintained this loss of energy must be made up by the collapse of gravitational energy.
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- This in an exploding star this whole process of collapse takes less than one second. The bounce of the collapsing star creates a great shockwave that expands into interstellar space at velocities approaching the speed of light.
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- The gas and particle compression that occurs as this shock wave smashes into the elements is what creates the higher isotopes of uranium (as well as all the other elements heavier than iron).
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- Radioactive decay is the timed release of this shockwave energy. Although the decay process for an individual particle, a neutron, is random, the statistical average of the decay in a sample of uranium follows this statistical average, known as the “half-life“. That half-life is how we determine the age of the Earth.
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- If we make this same radioactive material ratio measurements on the stars of our Milky Way galaxy, using spectroscopy, we can calculate a lower limit for the age of the Milky Way. It must be older than 8,000,000,000 years, twice as old as Earth and our Solar System.
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- If we assume that supernovae have been exploding at the same rate as we see today we can calculate the upper limit of the age of supernovae to be 13,000,000,000 years.
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- When scientists make calculations for the birth of globular clusters of galaxies they get 15,000,000,000 years ( + or - 3 billion years).
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- The birth of the Universe, the Big Bang, has been interpreted as a super radioactive process. The Universe starting as a single atom with an atomic weight equal to the total mass of the Universe.
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- The Universe we see is the result of repeated fission, or splitting, or decay, of this super atom. The diameter of the nucleus of this super atom would have been 30 times the diameter of our Sun. This dimension illustrates how much empty space exists inside every atom if we can condense the whole universe into this size 30 times larger than our Sun.. This is a 1920 theory by the astronomer Lemaitre, published in 1946.
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- Unfortunately this explosion concept became interpreted too literally. It was seen as an explosion of mass and energy rather than the birth of space and time.
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- All the scientists at that time were trying to use Einstein’s equations for Relativity to calculate the Big Bang process and the true age of the Universe. Including Einstein himself. His equations included the cosmological constant that he added to keep the Universe flat and static with his equation results.
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- Einstein later called it his “greatest blunder” when he learned from Edwin Hubble’s work that the universe was not static but expanding. And, that expansion term was causing the rate of expansion.
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- It was not until the 1960’s that new knowledge was added to our understanding of the Age of the Universe. This was the discovery of the “cosmic microwave background” radiation. This radiation is the leftover heat that occurred when the Big Bang first released its radiation.
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- The radiation has cooled to the point that instead of “gamma ray” radiation at millions of degrees temperature it is “microwave” radiation at 2.7 degrees Kelvin, or, -270.3 Centigrade.
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- The cosmic radiation may have started out uniform in temperature however as it spread out and interacted with galaxy clusters which contain interstellar gas at 100,000,000 degrees. This interaction boosts the energy of those photons to shorter wavelengths. That is, the radiation passing through a galaxy cluster get a bit hotter.
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- Counter intuitive to what we see the radiation gets boosted outside the range of our microwave receiver and it is effectively gone. It appears cooler rather than hotter in our microwave background picture. This apparent change of temperature in our picture is only .01%.
- The math of how these temperature variations are interpreted is beyond me. It involves computer modeling and much error analysis and many assumptions (inspired guesswork) that is over my head. This interpretation is also compared with several other methods used to date the Universe.
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- The age of the Universe is 13,700,000,000 years and waiting for the next new discovery. The time is incomprehensible to our lives. And, the fact that we can comprehend the age of the Universe is truly amazing. Stay tuned there is still more to learn....................
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March 8, 2022 UNIVERSE - Age of the Universe? 2117 3497
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